refactor!: introduces namespacing, error classes and renames legacy types

[andreydobrikov]

This pull request introduces several improvements and refactors to the Privy SDK, focusing on code style enforcement, namespace organization, and authentication logic. The main changes include strengthening code style guidelines, updating documentation, consolidating analytics and authentication namespaces, and refactoring exception handling and session management in the authentication flow.

Code style and documentation updates:

• Enhanced code style enforcement in .editorconfig to prefer auto-properties and expression-bodied methods, improving readability and maintainability.
• Updated CONTRIBUTING.md to clarify formatting rules and highlight key style preferences, making contribution guidelines clearer for new developers.

Namespace and interface organization:

• Refactored analytics-related files (ClientAnalyticsIdRepository, IAnalyticsManager, IAnalyticsRepository, IClientAnalyticsIdRepository) to use the Privy.Analytics namespace for better modularity and clarity. [1] [2] [3] [4]
• Updated authentication files (AuthDelegator, AuthRepository) to use Privy.Auth and related namespaces, aligning with new project structure. [1] [2]

Authentication logic and error handling:

• Replaced PrivyException.AuthenticationException with PrivyAuthenticationException throughout AuthDelegator, standardizing exception handling for authentication errors. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]
• Refactored session update logic in AuthDelegator to use a strongly-typed SessionUpdateAction enum instead of string literals, reducing bugs and improving code clarity.

SDK usage and documentation improvements:

• Improved SDK/README.md with clearer initialization instructions, explanation of authentication state handling, and updated wallet interface references for accuracy. [1] [2] [3]

Model and interface improvements:

• Changed AnalyticsEventRequestData properties to use C# auto-properties for consistency with code style rules.

These changes collectively improve code clarity, maintainability, and developer experience for the Privy SDK.

[lucasloisp]

This one's tough but given we know privyUser to be non-null here (because AuthState is authenticated: what do you think of removing the ?. check? I'd be fine with ! here.

An alternative from our other client SDKs is giving AuthState itself a User property that's always non-null in the Authenticated case.

Something potentially like this:

public abstract record AuthState
{
    // Prevent external inheritance to mimic the closed nature of an enum
    private AuthState() { }

    public record NotReady : AuthState;

    public record Unauthenticated : AuthState;

    public record Authenticated(IPrivyUser User) : AuthState;
}

Feel free to disagree! If we do like this: let's do in a separate PR 🙏

[andreydobrikov]

Agree, this maybe too defensive here.

[andreydobrikov]

Also, I think it's in the doc and we don't actually guard in the code anymore. Example here from our actual code.

            if (state == AuthState.Authenticated)
            {
                var user = await PrivyManager.Instance.GetUser();
                Debug.Log($"[privy.status] User ID: {user?.Id ?? "N/A"}");
            }

[lucasloisp]

Should this static method live instead in the LinkedAccountType class itself?

`LinkedAccountType.FromString(string type) -> LinkedAccountType

[andreydobrikov]

I can see a reasoning for that, but prefer to keep it here since it does not spill into public API and is clear responsibility at the response parsing level.

[lucasloisp]

Let's adjust the wording to "authorization key" over "signer"! That's the term we're using now in docs.

also the enum error code.

Suggested change

	throw new PrivyWalletException($"Failed to sign with user signer",
	EmbeddedWalletError.CreateAdditionalFailed); //Let this bubble up to HandleAuthStateChanged and AwaitConnected
	throw new PrivyWalletException($"Failed to sign with user's authorization key",
	EmbeddedWalletError.UserSignerRequestFailed); //Let this bubble up to HandleAuthStateChanged and AwaitConnected

[andreydobrikov]

Going to make this change as part of a separate PR since I refactored this class a bit and this is not longer relevant.